Targeting of NQ02 in CML

描述（由申请人提供）：伊马替尼被开发用于特异性靶向慢性髓性白血病（CML）中癌蛋白BCR-ABL的失调酪氨酸激酶活性，并且对主要激酶靶点具有高度特异性。在2007年的一项令人惊讶和意想不到的发现中，NQO 2在两项独立研究中被确定为伊马替尼的第一个非激酶靶点。发现伊马替尼有效且特异性地结合NQO 2，导致酶的催化活性的抑制。这两项研究的结论之一是NQO 2的抑制可能有助于伊马替尼在CML细胞中的治疗活性。在本提案中，我们将定义在CML中特异性靶向NQO 2的结果。尚未检查人类CML中的NQO 2水平，在目标1中，我们将表征一组伊马替尼初治和伊马替尼耐药的存档CML患者样本中的NQO 2水平。在目标2中，我们将研究是否使用我们实验室开发的基于新机制的（自杀）抑制剂特异性靶向NQO 2，在人CML细胞系中产生抗增殖活性。我们还将通过使用抗NQO 2 shRNA验证NQO 2在CML细胞增殖活性中的作用，并表征NQO 2稳定敲除对CML生长的影响。已知BCR-ABL稳定性受与其他蛋白质相互作用的影响。因此，在目标3中，我们将检查NQO 2和BCR-ABL之间是否存在蛋白质-蛋白质相互作用，这种相互作用是否被伊马替尼抑制，是否导致BCR-ABL稳定性增加以及是否依赖于NQO 2的催化活性。拟定的研究将描述NQO 2在伊马替尼治疗活性中的潜在作用，并确定特异性靶向NQO 2作为CML治疗方法的结局。公共卫生相关性：已发现伊马替尼有效且特异性地结合NQO 2，导致酶的催化活性的抑制。这项工作的含义是，抑制NQO 2可能有助于伊马替尼在慢性粒细胞白血病（CML）的治疗活性。拟议的研究将确定在CML中特异性靶向NQO 2的结果。新型NQO 2小分子自杀抑制剂的开发可能为CML的治疗提供新的途径。

DESCRIPTION (provided by applicant): Imatinib was developed to target specifically the deregulated tyrosine kinase activity of the oncoprotein BCR-ABL in chronic myeloid leukemia (CML) and it has high specificity against its major kinase target. In a surprising and unexpected finding in 2007, NQO2 was identified as the first non-kinase target of imatinib in two independent studies. Imatinib was found to bind potently and specifically to NQO2 resulting in inhibition of catalytic activity of the enzyme. One of the conclusions of these two studies was that inhibition of NQO2 may contribute to the therapeutic activity of imatinib in CML cells. In this proposal, we will define the outcome of specifically targeting NQO2 in CML. Levels of NQO2 have not been examined in human CML and in aim 1 we will characterize NQO2 levels in a panel of imatinib-naive and imatinib resistant archived CML patient samples. In aim 2, we will examine whether specific targeting of NQO2 using novel mechanism-based (suicide) inhibitors developed in our laboratory results in antiproliferative activity in human CML cell lines. We will also validate the role of NQO2 in the proliferative activity of CML cells by employing anti-NQO2 shRNA and characterize the effect of stable knockdown of NQO2 on CML growth. BCR-ABL stability is known to be influenced by interactions with other proteins. In aim 3, we will therefore examine whether there is a protein-protein interaction between NQO2 and BCR-ABL, whether this interaction is inhibited by imatinib, whether it leads to increased stability of BCR-ABL and whether it depends on the catalytic activity of NQO2. The proposed studies will characterize the potential role of NQO2 in the therapeutic activity of imatinib and define the outcome of specifically targeting NQO2 as a therapeutic approach in CML. PUBLIC HEALTH RELEVANCE: Imatinib has been found to bind potently and specifically to NQO2 resulting in inhibition of catalytic activity of the enzyme. The implication of this work is that inhibition of NQO2 may contribute to the therapeutic activity of imatinib in chronic myeloid leukemia (CML). The proposed studies will define the outcome of specifically targeting NQO2 in CML. The development of novel small molecule suicide inhibitors of NQO2 may provide a novel therapeutic approach in CML.